This invention relates generally to gas turbine engines, and more specifically to sump evacuation systems used with gas turbine engine engines.
A gas turbine engine typically includes at least one bearing assembly that rotatably supports a shaft. The bearing assembly is lubricated with oil, and heat from other engine components is absorbed and dissipated by the same oil. Accordingly, bearing assemblies are housed within sumps that include a supply pump that supplies lubricating oil under pressure to the bearing assemblies, and a scavenge pump that removes lubricating oil from the sump. The scavenge pump causes the return oil to pass through a heat exchanger prior to returning the oil to a tank or reservoir. The bearing assembly sumps also include seal assemblies that facilitate minimizing oil leakage from the sumps along the rotor shaft.
To further facilitate reducing oil from leaking from the bearing assembly sumps, at least some known bearing assembly sumps are also housed within pressurized cavities. The cavities include seal labyrinths that extend around the rotor shaft. During operation, compressed air is supplied to each surrounding pressurized cavity to maintain a positive pressure around the bearing assembly sump. Thus, oil leakage from the bearing assembly sump having the lower operating pressure to the pressurized cavity having the higher operating pressure is facilitated to be reduced.
However, during some engine operating conditions, the pressurization of the air supplied to the pressurized cavity may be insufficient to prevent the oil from leaking from the bearing assembly sump or seals. Moreover, because such leakage may be excessive, identifying a source of such leakage, and repairing the engine to prevent future leakage, may be a time-consuming and costly process.
In an exemplary embodiment, a sump evacuation system for a gas turbine facilitates reducing oil leakage from bearing assembly sumps in a cost-effective and reliable manner. The engine includes at least one bearing assembly. The sump evacuation system includes a sump pressurization cavity, a sump oil cavity, and an air pump. The bearing assembly is housed within the sump oil cavity and is coupled in flow communication with the sump pressurization cavity. The air pump is coupled in flow communication with the sump oil cavity.
During low-power or idle engine operations, the sump evacuation system is activated to facilitate preventing oil from inadvertently leaking from the sump oil cavity. More specifically, the sump evacuation system air pump draws air from the sump oil cavity, such that an operating pressure within the sump oil cavity is reduced below that of an operating pressure within the sump pressurization cavity. As a result, the oil is prevented from leaking from the lower pressure sump oil cavity during low-power or idle engine operations in a cost-effective and reliable manner.